Manufacture of aliphatic chloroepoxides by peracetic acid epoxidation under anhydrous conditions



United States Patent MANUFACTURE OF ALIPHATIC CHLOROEPOX- IDES BY PERACETIC ACID EPOXIDATION UN- DER ANHYDROUS CONDITIUNS Benjamin Phillips and Paul S. Starcher, Charleston,

W. Va., assignors to Union Carbide Corporation, a corporation of New Yorlr No Drawing. Filed Mar. 6, 1959, Ser. No. 797,586

7 Claims. (Cl. 260-3485) The present invention. relates to a novel process for the production of chloroepoxides by the epoxidation of allylic chloroalkenes with peracetic acid and has for an object the provision of a novel synthesis route for converting, expeditiously, allylic chloroalkenes to the corresponding chloroepoxides and the obtainment of products in high yields and high purity.

Heretofore according to customary practices haloalkenes have been oxidized with a variety of oxidizing agents including potassium permanganate, perbenzoic acid and the like. For example, Vallette, Ann. de Chimie 3:650, N0. 12, pp. 644-678 (1948), in describing the Work of Griner reacted 1,4-dibromobutene-2 with potassium permanganate to yield the 1,4-dibromo-2,3-dihydroxybutane.

Other existing oxidation processes of chloroalkenes comprise reacting allyl chloride With hypohalous acid to produce the hydroxychloride which is subsequently dehydrohalogcnated to produce epichlorohydrin, a chloroepoxide.

Similarly, Prileschajew (Berichte 59B, 194498 (1926)) reacted 2-chlorooctene-2 and perbenzoic acid for a period of 16 days. The only report of a product therein is the empirical structure C H Oc1 which is reported to be an epoxide, although duplicate experimental evidence using peracetic acid indicates that the product recovered in accordance with the teachings of Prileschajew is essentially an alpha-haloketone with small amounts of epoxide.

Surprisingly, it has been discovered that when allylic chloroalkenes and peracetic acid are reacted together, there are produced the corresponding chloroepoxides which are substantially free'of haloketones, stable in the reaction product and recoverable in high yields and of high purity. Furthermore, the reaction time to produce the corresponding chloroepoxides by reacting allylic chloroalkenes and peracetic acid has been reduced from l6 days according to the teachings'of Prileschajew to a time limit ranging from 17 minutes to about 8 hours.

It is an object of the present invention to provide a novel synthesis route for converting expeditiously, allylic chloroalkenes to the corresponding chloroepoxides.

A further object of this invention is the provision of a process which provides chloroepoxides in high yields and of high purity. 7

Another primary object of this invention is the provision of a novel total synthesis of chloroepoxides. in a single step by the reaction of allylic peracetic acid.

A further object of this invention is to provide a new route for the total synthesis of epichlorohydrin.

Other objects and advantages of thevinvention will be apparent from the following description thereof.

The starting materials to which the process of this invention is applicable are those aliphatic allylic chloroalkenes containing from three to ten carbon atoms in the skeletal chain and may be represented by the general formula:

chloroalkenes and wherein R R R R and R represent hydrogen, alkyl and chloroalkyl radicals.

As may be readily observed from the general formula, set forth above, the starting materials, that is, the aliphatic allylic chloroalkenes, possess in common at least one chlorine atom in the allylic position and no chlorine atoms joined directly to either of the olefinic carbon atoms.

It is well known in the art that the term allylic posi tion as used herein, refers to the position of the chlorine atom attached to the carbon atom which is adjacent to the carbon atoms containing the olefinic double bond. Expressed in terms of a molecular illustration the characteristic grouping referred to as the allylic position can be represented by the structure:

The starting materials are further limited by the fact that there are never more than two chlorine atoms in allylic positions which means that in any given compound only one of the radicals, R R or R may contain an allylic chlorine atom. Thus, for the purposes of illustration, such a compound may be depicted as follows: when R represents a chloroalkyl radical the molecule will contain two allylic chlorine atoms:

wherein R R R R R and R each represent an alkyl radical or a hydrogen atom. In the same manner R or R can contain the allylic chlorine atom and although more than one allylic position may be present in the starting material only two chlorine atoms may occupy the allylic positions.

The process of this invention comprises reacting under anhydrous conditions, an allylic chlorohydrocarbon hav ing the characteristic grouping:

and containing at least one chlorine atom in the allylic position and peracetic acid and recovering the corresponding chloroepoxide of high purity in high yields.

The reaction illustrating the process of this invention may be depicted as follows:

In carrying out the epoxidation reaction, the aliphatic, olefinic, allylic chlorohydrocarbon and the epoxidant are heated together. out at any convenient temperature desired depending on the nature of the starting material and the nature and concentration of the epoxidant employed. Suitable temperatures at which these epoxidation reactions can be carried out is a temperat re in the range of 40 C. to 150 (3., preferably in the range of 40 C. to C. The reaction conditions are maintained until an analysis for the epoxidant indicates that the desired amount of the epoxidizing agent has been consumed. After the reaction is complete, the reaction mixture can be worked up in any convenient manner and the chloroepoxide recovered by any convenient means, such as distillationor extraction.

The epoxidant employed in the process of the invention is peracetic acid and preferably in an inert solvent.

In general, the reaction can be carried 3. Typical inert solvents which can be used with the peracetic acid in this invention include acetone, ethyl acetate, butyl acetate, and dibutyl ether, among others. A method of preparation of peracetic acid is discussed in US. Patent No. 2,804,473.

Starting materials which can be readily employed and the resulting aliphatic chloroepoxides in accordance with this invention include:

Starting Materials Resulting Product 3-chl0r0-1,2-epoxypropane. 3-chloro-1,Zepoxybutane. l'chloro-2,3-epoxybutane. 3,4-dichloro-l,2-epoxybutane. 1,4-dichloro-2,3-epoxybutane. l-ehloro-2,3-epoxypcntane. 4-ch1or0-2,3 epoxypentane. 3-chloro-1,2-ep0sypentanc. l,4-dichloro-2,3-epoxypentane. l-chloro-2,3-epxyhexaue. 1,4dichloro-2,3-cpoxyhexaue. 2-ohloro-3,4-epoxyhexane. 2,5-dichloro-3,4-epoxyhcxa11e. 4-chlor0-2,3-epoxyhexaue. Lemme-2,3epoxyheptane. 1,4-(liehloro-2,3-epoxyheptanc. 4-chl0ro-2,3-cpoxyheptanc. 2-ch1oro-3,4-cpoxyheotana. -eh1oro3,4-epoxyheptano. 2,s-dichloro-3,4-epoxyheptauc. l-chloro-Z,3-epoxyoctaue. 4-chlor0-2,3-epoxyoctaue. 1,4-dichloro 2,3-epoxyoctano. 2.3-epoxy-2-ethylhexyl chloride. 3-chl0ro-4,depoxyoctauc. 3,6-dichl0r0-4,5-epoxyoctane. 2,5-dichl0ro-3,4 epoxyoctanc. 5-chl0ro-3,4-ep0xyoctane. 2-chloro-3-octene 2-chl0ro-3,4-ep0xyoctano. 1-chlor0-2-nonenc l-chloro-2,3 epoxynonane. 4-chl0ro-2noncne 4-chloro-2,3-epoxynonane. 1,4-dichloro-2-nonene l,4-dichloro-2,3-ep0xyu0nane. 2-chloro-3-nonene 2-chloro-3,4-epoxynonano. B-ohloro-Bnonene 5-chloro-3,4-epoxyn0na.ne. 2,5-diehloro-3-nonene 2,5-dichloro-3,4-epoxynonanc. 3'chloro-4-n0nene 3-chloro-4,5-ep0xynonaue. 6-chloro-4-n0nene ti chloro-lfi-epoxynonane. 3,6-dichloro-4-uoncne.- 3,6-diehlor04,5-epoxynonanc. 1-chloro-2-decene l-chloro-2,3-epoxydecane.

4-chlor0-2,3 epoxydecane.

1,4 dichloro-2,3-epoxydecane. .L- 2chloro-3,4-epoxydecane. 5-chloro-3,4-epoxydecaue. 2,5-dichloro-3,4-epoxydecane. 3-chlor0-4,5-epoxydecane. 6-chlor0-4-decene 6-chloro-4,:i-epoxydccaue. 3,6-dichloro-4-decene 3,6-dich1or0-4,S-epoxydecaue. 4-chloro-5-decene 4-chloro-5,6-ep0xydecaue. 4,7-dichlor0-5-decene 4,7-dichloro-5,6-ep0xy lccane.

3-chloro-l-propene-.. 3-chloro-l-butene 1-chloro-2-buteue 3,4-dich1oro-l-butene 1,4-dichloro-2-butene l-chloro-Z-pentene. 4-eh1oro-2-pentene. 3-chloro-1-pentene 1,4-dichloro-2-pente 1-ch1or0-2-hexene 1,4-dichloro-2-hexene 2-chloro-3-hexene. 2,5-dichl0ro-3-hexe 4-cl1loro-2-hexene. l-chloro-2-heptene. 1,4-dichloro-2hept 4-chloro-2-heptene. 2-chloro-3-heptene. 5-ehloro-3-heptene. 2,5-dichloro-3-heptc l-chloro-Z-oetene 2,5-dichloro-3-deceue 3-chloro4-decene The analysis for the epoxide group is based upon its reaction with pyridine hydrochloride to form the chlorohydrin and pyridine. Into a pressure bottle containing 25 milliliters of l N pyridine hydrochloride in chloroform was introduced a sample of epoxide calculated to use about 50 percent of the pyridine hydrochloride. The bottle was then closed and the contents heated in a steam bath for a period of one hour. At the end of that time the bottle and contents were cooled, drops of phenolphthalein indicator (1.0 gram per 100 milliliters of 60 percent ethanol) added, and the mixture titrated to a permanent red endpoint with standard 0.2 N alcoholic potassium hydroxide solution. A blank was also run in precisely the same fashion except that the sample was omitted.

A distinct advantage of the process of this invention is the production of epichlorohydrin of high purity and in high yield in a single-step process which permits a convenient continuous operation. The present commercial process for the production of epichlorohydrin, mentioned hereinbefore, is an example of the well known halohydrin route which involves the addition of hypochlorous acidto allyl chloride and subsequent dehydrohalogenation with sodium hydroxide to produce epichlorohydrin, salt and water. This commercial process suffers from the serious economic disadvantage that it requires the consumption of one mol of hypochlorous acid and one mol of base to produce epichlorohydrin from allyl chloride. 7

Additionally, there is also the recovery or waste prob- CIl lem of the co-product sodium chloride. Furthermore, problems of corrosion are encountered in handling aqueous sodium chloride, and the use of special, more expensive, equipment is necessary to avoid this corrosion.

An advantage of the process of this invention is the production of a single product of known structure. Frequently the halohydrin route fails to yield a pure compound. This problem is especially true When one attempts to prepare the epoxide of dihaloalkene. For example, the addition of hypochlorous acid to 1,4-dichloro- Z-butene yields a compound:

which on dehydrohalogenation with base gives a mixture of:

CH2CHCHCH 0 d1 All and OlGHzCHOHCH Cl The problem is also encountered with many monohaloalkenes such as, for example, crotyl chloride. Addition of hypochlorous acid to crotyl chloride gives a mixture of:

and

OHs(|Jl1-(|3HOH:C1

which on dehydrohalogenation with base yields a mixture The synthesis of epichlorohydrin mentioned hereinbe fore is one of the few cases where a single product is obtained since when either chlorine atom of glycerol dichlorohydrin is removed by dehydrohalogenation the same product results.

The present application is a continuation-in-part of our copending application Serial No. 439,878, filed June 28, 1954, now abandoned.

The following examples serve to illustrate the practice of the invention.

EXAMPLE I Preparation of Chloroisobutylene Oxide From Methallyl Chloride and Peracetic Acid Methallyl chloride (533 grams) containing 0.2 percent of pyrogallol inhibitor was heated under reflux at atmospheric pressure (kettle temperature 72 C. )"in a kettle equipped with a 3-foot column packed with glass helices. Over a period of 2 hours and 20 minutes, 502 grams of a 30.2 percent solution of peracetic acid in acetone was added to the kettle- The kettletemperature remained at 72 C. throughout the addition. After an additional 2.5 hour reaction period the reaction mixture was allowed to stand overnight at room temperature. The reaction mixture was then fractionally distilled. A percent yield of chloroisobutylene oxide was obtained in a cut boiling at 40 C. to 50 C. at 50 mm. pressure which contained about equal weights of acetic acid and the oxide. A portion of this mixture was steam distilled under 260 mm. pressure. The chloroisobutylene oxide came over at 58 C. and separated out as a lower layer which was continuously removed. After drying, the oil layer (11 1.4280) analyzed 99.5 percent as chloroisobutylene oxide,

using pyridine hydrochloride in chloroform as the analytical reagent.

EXAMPLE 11 Preparation of 3-Chlor0-1,Z-Epoxybutane From 3- Cltloro-I-Butene and Peracetic Acid A solution of peracetic acid (1460 grams of a 20.7 percent solution) in acetone was added dropwise over a period of 4 hours to 1448 grams of 3-chloro-1-butene containing 2.8 grams of trinitrobenzene as an inhibitor. The temperature Was maintained at 58 C. to 60 C. throughout the addition. An additional 8-hour reaction period at this same temperature was required before the peracetic acid was substantially all reacted (91 percent). The reaction mixture was stripped of excess chloroalkene and acetone under reduced pressure. The residue was diluted with 500 grams of carbon tetrachloride and washed three times with water to remove acetic acid. The washed oil layer was then distilled under reduced pressure. The cuts boiling between C. and C. at 50 mm. pressure had a purity of 90.5 percent as judged by an analysis for epoxide by the pyridine-hydrochloride in chloroform method. Distillation of the water Wash material gave additional epoxide. The combined yield, based on peracetic acid, was 63 percent of the theoretical.

EXAMPLE Ill Preparation of 1,4-Dichloro-2,3-Ep0xybutane From 1,4-Dichloro-2-Butene and Peracetic Acid A solution of peracetic acid in acetone (78 grams of a 21.5 percent solution) was fed dropwise with stirring to a flask containing 1000 grams of 1,4-dichloro-2-butene at C. After adding approximately one-half of the peracetic acid, an analysis indicated that the reaction was proceeding slowly. The temperature was raised to 80 C. to 88 C. and the addition continued. A total of 4 hours was required for the addition to be completed. The reaction was continued for an additional 2 hours at 80 C. to 88 C. After standing overnight at room temperature the reaction mixture was fractionally distilled. The product, 1,4-dichloro 2,3-epoxybutane, had the following properties:

EXAMPLE IV Preparation of Epichlorohydrin From Allyl Chloride and Pcracetic Acid A solution (256 grams) of peracetic acid (32.7 percent) in acetone containing 0.5 gram of sodium pyrophosphate was added dropwise over a period of 1 hour to a kettle of boiling allyl chloride (430 grams). The reaction mixture was heated under reflux (temperature 50 C. to 5 3 C.) for an additional 6 hours, at which time an analysis for peracetic acid indicated that 89 percent of it had reacted. The excess allyl chloride and acetone were removed from the reaction mixture by distillation at 170 mm. pressure. The pressure was reduced and the product, epichlorohydrin, was distilled as a mixture with acetic acid. The epichlorohydrin and acetic acid were separated by steam distillation under reduced pressure (120 mm) The lower layer was removed continuously from the distillate, dried over sodium sulfate, and distilled on a Vigreux column to give a 50 percent yield of epichlorohydrin having a boiling point of 52 C. at 74 mm. pres sure.

6 EXAMPLE v Preparation of Epichlorohydrin A method of analysis for epichlorohydrin in the pres ence of acetic acid and allyl chloride was developed and checked against synthetic mixtures. The method involved the reaction of pyridinium chloride in chloroform solution with epichlorohydrin with a correction made for the acetic acid present. This method gave accurate values for known compositions of acetic acid, epichlorohydrin, and allyl chloride.

A series of runs was made in a stainless steel bomb to check the eilect of a sequestering agent and various inhibitors on the reaction between peracetic acid and allyl chloride. At the end of the reaction the reaction mixtures were distilled and were analyzed by the above method. This gave an accurate value of the yield of epichlorohydrin. The losses and the time involved in separating epichlorohydrin from acetic acid on a small scale were thus eliminated. In each of these runs the molar ratio of allyl chloride to peracetic acid was 5 to 1, and the reaction temperature was 60 C. The sequestering agent was N21 (Z-ethylhexyl) (P O Victawet 35B. A summary of these runs is given in the following table:

EXAMPLE VI Continzlous Preparation of Epichlorohydrin at C.

Epichlorohydrin was prepared continuously by passage of a mixture of allyl chloride and peracetic acid solution through a stainless steel coil under pressure and heated to 100 C. with steam. The following charge stock was made up:

Allyl chloride grams 530 35% solution of Victawet 353 in acetic acid cc 0.95 Peracetic acid solution in acetone (24.7%) "grams" 451 and put under 75 pounds per square inch nitrogen pressure and passed through a coil made of As-inch stainless steel tubing having a volume of 67 cc. The tube effluent was analyzed for peracetic acid and for epichlorohydrin as described in Example V. The results are recorded in the following table:

Feed contact Yield of Run Temp, Pressure, Peracetic epicliloro- No. C. p.s.i. consumed, hydrin, Rate, Time, percent percent ccjhr. minutes EXAMPLE VII Preparation of 3,4-Dichl0r0-1,Z-Epoxybutane Twenty mols (2500 grams) of 3,4-dichloro-1-butene was placed in a B-necked, S-liter flask equipped with a stirrer, thermometer, and dropping funnel. A weight of 2.5 grams (0.1% by weight of the olefin) of Na;, (2-ethylh y 5 3 10 2 Victawet 35B, was added as a stabilizer. Then, with stirring at 75 5 mols of 25.0 percent peracetic acid in ace tone was added over a 3-hour period. After heating for an additional 1.5 hours, analysis for peracetic acid showed that a conversion of 89 percent had been achieved.

The reaction mixture was charged to a distillation kettle attached to a packed 24-inch glass column. Then at 50, the acetic acid and acetone were removed by flash distillation. It was observed that the last amounts of acetic acid distilled as an azeotrope with unreacted 3,4-dichloro-1- butene. The remaining material was carefully fractionated to obtain pure unreacted olefin and the desired epoxide. A total of 471 grams (75 percent) of 3,4-dichloro 1,2-epoxybutane was obtained. The epoxide distilled at 43 at 2 mm. pressure. An index of refraction of 11 1.4740 was observed for this compound. An analysis for epoxide by the pyridine hydrochloride in chloroform method indicated a purity of 93.3 percent. However, no foreign groups such as olefin, carbonyl, or hydroxyl were found to be present by an examination of the infrared absorption spectrum. Redistillation gave material of the same physical properties, indicative of the presence of a single compound.

EXAMPLE VIII Preparation of 2,3-Epoxy-2-Ethylhexyl Chloride (a) PREPARATION OF THE UNSATURATED HALIDE To a mixture of 256 grams of 2-ethyl-2-hexenol and 167 grams of pyridine was added, over a period of 2.3 hours, 319 grams of thionyl chloride at a temperature of approximately C. -The reaction mixture was then held at C. for 1 hour and then heated to 70 C. for an additional 3 hours. The reaction mixture was cooled, diluted with 600 cc. of hexane, and poured into 1500 grams of ice and water with vigorous agitation. The organic layer was separated and washed twice with dilute sodium carbonate solution. Distillation gave a 49 percent yield of 2-ethyl-2-hexe nyl chloride having a boiling point of 52 C. to 54 C. at mm. pressure and a refractive index range of 1.44491.4485 (r1 The refractive index range is probably. due to the products being a mixture of cis and trans isomers. Analysis for allylic chlorine by saponification and determination of chloride ion by the Volhard method indicated a purity of 92 percent. Quantitative bromination analysis indicated a purity of 96 percent.

(b) PREPARATION OF THE EPOXIDE A solution of peracetic acid in acetone (390 grams of a 22 percent solution) was added over a period of 1.5 hours to 110 grams of 2-ethyl-2-hexenyl chloride at a temperature of 40 C. The temperature was raised to 50 C. and the reaction allowed to continue for an additional 4 hours. Toluene (300 cc.) was added, and the acetone was removed by distillation under reduced pressure. The residue was washed with water to remove acetic acid and then fractionated under reduced pressure. A 57 percent yield of 2,3-epoxy-2-ethylhexyl chloride, a colorless liquid boiling at 70 C. to 71 C. at 10 mm. pressure and having a refractive index of 1.4420 (11 was obtained. An analysis by the pyridinium-chloridein-chloroform method for epoxide indicated a purity of 94 percent.

EXAMPLE IX Preparation of Z-Chlorooctenes According to the teachings of Prileschajew (Berichte 59B, 194-198 (1926)), 458 grams of phosphorus pentachloride was added dropwise over a 2-hour period to 250.4 grams of n-hexyl methylketone with stirring. The temperature was maintained in the 0 C. to 10 C. range by cooling the flask with a Dry Ice-acetone bath. After an additional 2-hour reaction period at 10 to 12C. the reaction mixture was added dropwise over a 1.5-hour period to asolutio'n of 600 grams of sodium hydroxide in 2 liters of water. The neutralized mixture was filtered to remove the salt and the layers were separated. Distillation of the oil layer gave 78 grams (27 percent yield) of 2-chlorooctenes boiling at 83-85 C. at 50 millimeters and having a refractive index range of 1.43561.4366 (11 Examination of the infrared spectrum (bands at 6.08 and 6.2 and at 11.4 and 12.35;) of this product indicated that it was a mixture of 2-chloro-l-octene and 2- ch1oro-2-octene.

EXAMPLE X Reaction of Pei-acetic Acid With Z-Chlorooctenes T o grams of the 2-chloro-2(1)-octene mixture above, was added 224 grams of a 25.4 percent solution of per acetic acid in ethyl acetate. The temperature was maintained at room temperature for 17 days under conditions which were analogous to the teachings of Prileschajew (Berichte 59B, 194-198 (1926)). The products were isolated by distillation after first azeotroping the volatiles with ethylbenzene. Approximately 24 grams of reaction product was obtained. Infrared analysis indicated a mixture of epoxide and chloroketone, with the chloroketone predominating.

What is claimed is:

1. A process which comprises contacting a chloroolefin compound of the formula:

wherein R R R R and R are selected from the group consisting of hydrogen, a-lkyl, and chloroalkyl, said chloroolefin compound containing from 3 to 10 carbon atoms and a maximum of two chlorine atoms in allylic positions; with peracetic acid, under anhydrous conditions, at a temperature in the range of from about 40 C. to about 150 C., for a period of time sufficient to produce the corresponding monoepoxide.

2. The process of claim 1 wherein the reaction is carried out at a temperature in the range of from about 40 C. to about C.

3. The process for the production of 3-chloro-1,2- epoxybutane which comprises contacting 3-chloro-l-butene with peracetic acid, under anhydrous conditions, at a temperature in the range of from about 40 C. to about 130 C., for a period of time suflicient to produce 3- ch1oro-1,2-epoxybutane.

4. The process for the production of 1,4-dich1oro-2,3--

epoxybut-ane which comprises contacting 1,4-dichloro-2- butene with peracetic acid, under anhydrous conditions, at a temperature in the range of from about 40 C. to about 130 C., for a period of time sufiicient to produce 1,4-dichloro-2,3-epoxybutane.

5. The process for the production of epio'hlorohydrin' enyl chloride with peracetic acid, under anhydrous conditions, at a temperature in the range of from about 40 C. to about 130 C., for a period of time suflicient to produce 2,3-epoxy-2-ethylhexyl chloride.

References Cited in the file of this patent UNITED STATES PATENTS Levy Mar. 8, 1949 (Uther references on following page) UNITED STATES PATENTS Swern et a1 Dec. 27, 1949 Phillips et a1. Mar. 12, 1957 Starcher et a1 Nov. 18, 1958 FOREIGN PATENTS France Nov. 12, 1956 Italy Apr. 18, 1956 19 OTHER REFERENCES Prileschajew: Berichte, v01. 59B, pages 194-198 (1926). Swern: Chem. Reviews, v01. 45, pp. 1-68 (1949). The Condensed Chemical Dictionary, 5th ed,, Reinhold 5 Pub. Corp, 1956, p. 6.

Bradley et a1.: J. Chem. Sec. (Lon.), 1951, pages 2877 to 2883. 

1. A PROCESS WHICH COMPRISES CONTACTING A CHLOROELFIN COMPOUND OF THE FORMULA: 